Re: sparse -Wptr-subtraction-blows: still needed?

From: Andi Kleen
Date: Wed May 02 2007 - 08:06:50 EST


Dave Jones <davej@xxxxxxxxxx> writes:
>
> #define __page_to_pfn(page) ((unsigned long)((page) - mem_map) + \
> ARCH_PFN_OFFSET)
>
> looks like the other two variants of __page_to_pfn also use similar arithmatic.

No way around this. The only way to turn a page into a pfn is to do
a constant division. Should be fairly cheap here though.

-Andi (who thinks the sparse warning is dumb; better to look at oprofiles
of hot paths)
-
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